node-flick/js/NodeFlick.js

NodeFlick.js revision 431adebef2d65f5c73809006d3f032ef98d25c27
   var HOST = "host",
       PARENT_NODE = "parentNode",
       BOUNDING_BOX = "boundingBox",
       OFFSET_HEIGHT = "offsetHeight",
       OFFSET_WIDTH = "offsetWidth",
       BOUNCE = "bounce",
       MIN_DISTANCE = "minDistance",
       MIN_VELOCITY = "minVelocity",
       BOUNCE_DISTANCE = "bounceDistance",
       DECELERATION = "deceleration",
       STEP = "step",
       DURATION = "duration",
       EASING = "easing",
       FLICK = "flick";

   function Flick(config) {
       Flick.superclass.constructor.apply(this, arguments);
   }

   Flick.ATTRS = {

       deceleration : {
           value: 0.98
       },

       bounce : {
           value: 0.7
       },

       bounceDistance : {
           value: 150
       },

       minVelocity : {
           value: 0
       },

       minDistance : {
           value: 10
       },

       boundingBox : {
           valueFn : function() {
               return this.get(HOST).get(PARENT_NODE);
           }
       },

       step : {
           value:10
       },

       duration : {},

       easing : {}
   };

   Flick.NAME = "pluginFlick";
   Flick.NS = "flick";

   Y.extend(Flick, Y.Plugin.Base, {

       initializer : function() {
           this._node = this.get(HOST);

           this.setBounds();
           this._setStyles();

           this._node.on(FLICK, Y.bind(this._onFlick, this), {
               minDistance : this.get(MIN_DISTANCE),
               minVelocity : this.get(MIN_VELOCITY)
           });
       },

       setBounds : function () {
           var box = this.get(BOUNDING_BOX),

               boxHeight = box.get(OFFSET_HEIGHT),
               boxWidth = box.get(OFFSET_WIDTH),

               contentHeight = this._node.get(OFFSET_HEIGHT),
               contentWidth = this._node.get(OFFSET_WIDTH);

           if (contentHeight > boxHeight) {
               this._maxY = contentHeight - boxHeight;
               this._minY = 0;
               this._scrollY = true;
           }

           if (contentWidth > boxWidth) {
               this._maxX = contentWidth - boxWidth;
               this._minX = 0;
               this._scrollX = true;
           }

           this._x = this._y = 0;
       },

       _setStyles : function() {
           var box = this.get(BOUNDING_BOX);

           // TODO: Cross-browser and class based
           box.setStyle("overflow", "hidden");

           if (box.getStyle("position") !== "absolute") {
               box.setStyle("position", "relative");
           }

           this._node.setStyle("position", "absolute");
       },

       /**
        * Execute a flick at the end of a scroll action
        *
        * @method _flick
        * @param distance {Number} The distance (in px) the user scrolled before the flick
        * @param time {Number} The number of ms the scroll event lasted before the flick
        * @protected
        */
       _onFlick: function(e) {
           this._v = e.flick.velocity * e.flick.direction;
           this._flick = true;

           this._flickAnim();
       },

       /**
        * Execute a single frame in the flick animation
        *
        * @method _flickFrame
        * @protected
        */
       _flickAnim: function() {

           var y = this._y,
               x = this._x,
               maxY = this._maxY,
               minY = this._minY,
               maxX = this._maxX,
               minX = this._minX,
               velocity = this._v,

               step = this.get(STEP),
               deceleration = this.get(DECELERATION),
               bounce = this.get(BOUNCE);

           this._v = (velocity * deceleration);

           if (this._scrollX) {
               x = x - (velocity * step);
           }

           if (this._scrollY) {
               y = y - (velocity * step);
           }

           if (Math.abs(velocity).toFixed(4) <= 0.015) {

               this._flick = false;

               this._killTimer(!(this._exceededYBoundary || this._exceededXBoundary));

               if (this._scrollX) {
                   if (x < minX) {
                       this._snapToEdge = true;
                       this._setX(minX);
                   } else if (x > maxX) {
                       this._snapToEdge = true;
                       this._setX(maxX);
                   }
               }

               if (this._scrollY) {
                   if (y < minY) {
                       this._snapToEdge = true;
                       this._setY(minY);
                   } else if (y > maxY) {
                       this._snapToEdge = true;
                       this._setY(maxY);
                   }
               }

           } else {

               if (this._scrollX && (x < minX || x > maxX)) {
                   this._exceededXBoundary = true;
                   this._v *= bounce;
               }

               if (this._scrollY && (y < minY || y > maxY)) {
                   this._exceededYBoundary = true;
                   this._v *= bounce;
               }


               if (this._scrollX) {
                   this._setX(x);
               }

               if (this._scrollY) {
                   this._setY(y);
               }

               this._flickTimer = Y.later(step, this, this._flickAnim);
           }
       },

       _setX : function(val) {
           this._move(val, null, this.get(DURATION), this.get(EASING));
       },

       _setY : function(val) {
           this._move(null, val, this.get(DURATION), this.get(EASING));
       },

       _move: function(x, y, duration, easing) {

           if (x !== null) {
               x = this._bounce(x);
           } else {
               x = this._x;
           }

           if (y !== null) {
               y = this._bounce(y);
           } else {
               y = this._y;
           }

           duration = duration || this._snapToEdge ? 400 : 0;
           easing = easing || this._snapToEdge ? 'ease-out' : null;

           this._x = x;
           this._y = y;

           this._anim(x, y, duration, easing);
       },

       _anim : function(x, y, duration, easing) {
           var node = this._node;

           // TODO: Integrate Anim, once done

           if(duration) {
               easing = easing || 'cubic-bezier(0, 0.1, 0, 1.0)';
               node.setStyle('-webkit-transition', duration+'ms -webkit-transform');
               node.setStyle('-webkit-transition-timing-function', easing);
           } else {
               node.setStyle('-webkit-transition', null);
               node.setStyle('-webkit-transition-timing-function', null);
           }

           node.setStyle('-webkit-transform', 'translate3d('+(x*-1)+'px,'+(y*-1)+'px,0)');
       },

       _bounce : function(val, max) {
           var bounce = this.get(BOUNCE),
               dist = this.get(BOUNCE_DISTANCE),
               min = bounce ? -dist : 0;

           max = bounce ? max + dist : max;

           if(!bounce) {
               if(val < min) {
                   val = min;
               } else if(val > max) {
                   val = max;
               }
           }
           return val;
       },

       /**
        * Stop the animation timer
        *
        * @method _killTimer
        * @param fireEvent {Boolean} If true, fire the scrollEnd event
        * @private
        */
       _killTimer: function(fireEvent) {
           if(this._flickTimer) {
               this._flickTimer.cancel();
           }

           if(fireEvent) {
               // this.fire(EV_SCROLL_END);
           }
       }
   });

   Y.Plugin.Flick = Flick;